Low stretch sectional abrasive belts

ABSTRACT

A relatively heavy woven fabric is provided of such construction and finish that, when used as a backing member for coated abrasive material, a sectional abrasive belt can be manufactured of desirably low stretch characteristics.

1161M States Patent ['19] Okrepkie et a1.

LOW STRETCH SECTIONAL ABRASIVE BELTS Inventors: John Okrepkie, Troy, N.Y.; Henry J. Swiatek, Mentor,- Ohio Assignee: Norton Company, Troy, N.Y.

Filed: June 7, 1971 Appl. No.: 150,306

US. Cl .1. 161/87, 51/188, 51/193, 51/295, 51/297, 51/298, 117/33, 156/279, 161/36, 161/91, 161/94, 161/162 Int. Cl ..B24d 11/00 Field of Search..... 51/295, 298, 188, 193, 297; 117/33; 74/232; 156/279; 161/87, 91, 162,

[ Jan. 22, 1974 [56] References Cited UNITED STATES PATENTS 2,805,136 9/1957 Neil et a1. 51/298 3,053,020 9/1962 Bratton 51/188 3,296,022 l/l967 Timmer et a1. 117/161 3,413,106 l1/1968 Argiro 51/295 Primary Examiner-William A. Powell Attorney, Agent, or Firm--Herbert L. Gatewood [5 7] ABSTRACT A relatively heavy woven fabric is provided of such construction and finish that, when used as a backing member for coated abrasive material, a sectional abrasive belt can be manufactured of desirably low stretch characteristics.

; 6 Claims, 2 Drawing Figures PATENTEHJANZZW' 3'. 787. 273

, Sectional Belt I Running Dlrecfion M750 Yarns /7 Fill Yarns 5807/0 of 600764 Abrasive Material Fig. 2.

/n venfors John Okrep/w'e (4,, r I

The/r Attorney.

. LOW STRETCH SECTIONAL ABRASIVE BELTS BACKGROUND OF INVENTION 1. Field of the Invention This invention relates to a finished woven fabric particularly suitable as a backing member in the manufacture of coated abrasive material and to the method of manufacture of such a fabric backing member. More specifically, this invention is concerned with sectional abrasive belts of improved operating characteristics and their manner of manufacture.

2. Description of the Prior Art Coated abrasive belts inmost instances do not exceed the width of the coated abrasive material from which they are manufactured. Moreover, inherent limitations in presently existing apparatus in the coated abrasive industry, particularly in the adhesive coating apparatus, generally preclude the manufacture of coated abrasive material in widths greater than about 52 inches. However, over the years, there has developed a need, e.g., the production of steel sheets and the like in widths approaching 100 inches, for abrasive belts of greater width than coated abrasive material conventionally made. The manufacture of such wide abrasive belts, e.g., upwards of IOO inches in width, has, as is believed obvious, posed aserious problem to the coated abrasive industry.

It has been proposed heretofore to manufacture wide coated abrasive belts by joining together a desired number of sections of coated abrasive material. One technique for making these so-called sectional belts has involved cutting a wide web of coated abrasive material into a series of parallelograms and adhesively joining these parallelograms together along their longer sides. The abrasive belt so manufactured, in order to provide a belt of greater width and of desirable operating characteristics, necessarily has the warp yarns of the backing member disposed at an angle to the running direction of the sectional belt. This angle in general will be in excess of 45 with respect to the running direction of the sectional belt so that the strength and stretch of the belt are determined in large part by the cross tensile strength and'cross stretch, respectively, of the backingmember of the coated abrasive material from which the parallelogram shaped sections are cut.

provement in sectional abrasive belts, the search has continued for even further improvement in the stretch characteristics of such wide belts.

SUMMARY OF THE INVENTION Our invention provides a woven fabric of such construction and finish that it will be found particularly suitable as a backing member for the manufacture of sectional abrasive belts. With such finished fabrics as found useful herein, sectional-belts can be manufactured having low stretch characteristics, i.e., 4 percent elongation at lbs./in. width tensile strength in the running direction of the belt.

The woven fabrics which have been found useful in the practice of the invention are relatively heavy, are of maximum construction as exemplified by a fabric cover of at least about 98 percent, and are finished with a resinous front size that penetrates into the woven fabric to the extent of at least about 50 percent of the fabric thickness. In a preferred aspect of the invention, there is included in combination with the resinous front size a nonslip material.

Thus, a relatively stiff, dimensionally stable woven fabric is provided that, when used as a backing member for coated abrasive material and such material is used in the manufacture of sectionalabrasive belts, the belts, during usage, will not disadvantageously stretch due to excessive distortion of the woven backing member.

Too much stretch is undesired as it presents tracking problems as well as, in some cases, belt breakage resulting from fold over in an excessively elongated belt.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood hereinafter in reading the detailed description thereof in conjunction with reference to the accompanying drawing in which:

Flg. l is a view, greatly enlarged, in cross-section of a web of coated abrasive material utilizing as a backing member a woven fabric in accordance with the invention; and

FIG. 2 is a plan view of a section of an endless sectional abrasive belt utilizing parallelogram shaped sections of the abrasive material shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS Referring to the drawing, there is disclosed in FIG. 1, coated abrasive materal 10 comprising a woven fabric backing member 11, maker adhesive 12, abrasive grains l3, and sand size coat 14.

Backing member 11, as is conventional, is backfilled and provided with a backsize and, as hereinafter more fully disclosed, in the preferred aspect of the invention is impregnated with a non-slip agent, all of which for sake of clarity is not shown in the drawing. On the front side of backing member 11 there is provided a resinous front size 15. The latter. material forms a relatively smooth, thin, continuous layer on the surface of backing member 11, and, in accordance with our invention, is seen to penetrate into the woven fabric backing member to the extent of at least about 50 percent of the fabric thickness.

Although backing member 11 may be woven from yarns of various fibrous materials, for example, cotton, polyamides, polyesters, polynosics, and blends thereof, the preferred backing member is a relatively heavy woven cotton cloth, i.e., one weighing about 12 ounces per square yard. Such a fabric, when finished as hereinafter more fully described, will provide a backing member for coated abrasive manufacture that is relatively stiff and dimensionally stable. Those skilled in the coated abrasive art will readily appreciate, however, that these desired physical characteristics may be achieved with other weight fabrics by suitably altering the manner of processing and handling of the coated abrasive material so manufactured, for example, flexing, curl correction, humidification, etc..

Woven fabrics which in general will be found suitable .in the practice of theinvention are of maximum construction, i.e., for a given set of warp and fill yarns, the maximum amount of yarn that can be woven in a particular construction without buckling or jamming during weaving. As will be appreciated by. those skilled in the textile art, selection of, e.g., a warp yarn of certain yarn number, will permit design of a-whole family of fabrics of various yarn-counts and numbers, warp and fill, and of different waves. In general, however, it is desirable that the fill yarns be stronger than the warp yarns, or that, at least such yarns be so selected that on finishing of the woven fabric, the tensile strength in the fill direction will be at least equal to that in the warp direction so that the desired strength and stretch properties will-be obtained in a'sectional abrasive belt.

We have discovered that a fabric of suitable maxiprove the fiber-to-fiber friction characteristics within the woven fabric. Thus, they contribute somewhat-to dimensional stability of the fabric; however, used alone, it has been found, such materials do not provide the desired dimensional stability and attendant resistance to elongation which makes for a sectional belt having the required low stretch characteristics, i.e., no more than about 4 percent elongation at 100 lbs/in. width tensile strength.

Although the amount of slip agent in the fabric may be varied somewhat, depending on the specific-agent used and the particular characteristics desired, satisfactory results will be obtained when, for example, the

3 amount Rexoslip AS applied, dry weight, is from about mum construction is one having-a fabric cover of at least about 98 percent, such'a construction and fabric cover providing a fabric, when finished as hereinafter described, of the desired dimensional stability for manufacture of sectional abrasive belts.

Fabric cover, as known by those skilled in the textile art, is determined by the difference between 100 percent and the percent of air space in the-fabric. Assuming regular twist yarns and that the formula for maximum diameter per inch is 28 VW, where N is the yarn number, then warp cover warp ends per inch/28 V N, and

% filling cover fill ends per inch/28 V N; I

The difference between 100% and the percent cover is the air space in each direction; therefore, the fabric air space is determined by multiplying these two results together. Thus, for a cotton sateens of standard construction, e.g., 1.12 yards/1b., a yarn count 96 X 60, yarn numbers l7s warp and'9.5s fill warp cover 96/28 W 0.835 83.5% fillcover 60/28 V9? 0.695 69.5% air space (0.165) 0.305 0.050 5.0% fabric cover 100% 5.0% 95.0%

On the other hand, a cotton sateens fabric woven with the maximum number of warp and till ends possible without jamming or buckling during weaving, e.g., weave 4/1, 104 X 60, l7s X 6.5s, has a cover of about 98.5%. It is such fabrics as this of maximum construction that have been found to have the desired dimensional stability and to be suitable in avoiding undue stretch in sectionalabrasive belts.

Various non-slipagents may be used in the practice of the invention; however, one found particularly suitable is Rexoslip AS, a mixture of hydrogenerated resins commercially available from Emkay Chemical Co. of

Elizabeth,iNew Jersey. Other such materials which may be used include Rexoslip, a protein concentrate terpene resin blend; Rexoslip Concentrate, a gum resin mixture with amino weighter; Doo-Co-Stat D-l005', an ethoxylated fatty acid ester, from Dooly Chemical of 0.5 to about 2.5 lbs. persandpaper makers ream. The preferred amount is about 1.8 i 0.3 lbs. per sandpaper makers team. In certain instances, for example, where pull down during cloth finishing less than about 5 percent, satisfactory results may be obtained without any non-slip agent in the fabric.- However, dimensional stability of the fabric will be noticeably improved when a non-slip agent is used in combination with the front size and will be even further improved when pull down is the minimum amount possible. In any event, pull down resulting from finishing should not exceed 5 percent, and preferably should be 0 percent.

Front size 15 is a resinous material which in a suitable composition, on application thereof and with proper drying, penetrates into the high cover fabric. On evapo- 0 ration of the carrier, the resinous material deposits itparting the desired degree of stiffness and dimensional Chatanooga, Tenn.; and Non-Slip DF,,a solubilized natural resin, from Hart Products Corporation of New York, N.Y. These agents as will be appreciated, im-

stability to the fabric construction. The woven fabric must be saturated, it has been determined, with sufficient composition and to such an extent that'the front size material on drying penetrates to a depth of at least about 50 percent of the thickness of the fabric. The amount of front size material applied will depend, of course, to some extent on the stiffness desired in and which can be tolerated in the coated abrasive backing member. However, by way of example, where a maximum construction sateens as before described is used as the backing member, the amount of front size can vary from about 4.8 to about 8.5 lbs. per sandpaper makers ream. The preferred amount of resinous front size in the fabric is about 6.8 i 0.9 lbs. (dry weight) per sandpaper makers ream.

Various heat-hardenable resinous materials may be used for the front size material. However, such material, in addition to being heat hardenable, must be miscible and compatible with the maker adhesive. A resinous material that we have found particularly useful involves a combination of phenol-formaldehyde resol resins having different curing characteristics. Other resinous material which may be used in the practice of the invention include any resol phenolic resin in a composition that will penetrate suitably into the fabric, e.g., those having curing temperatures up to about 300F, as well as heat-hardenable epoxy resins, urea formaldehyde and polyesters.

The maker adhesive can be of any of those heathardenable resinous materials conventionally used in the manufacture of coated abrasive material provided such resinous material is, compatible and miscible with the resin front size. This feature is essential to provide a non-shearing adhesive bond between the maker adhesive and the backing member. Suitable such heathardenable resins include phenolics, polyesters, epoxies, and urea-formaldehyde. Particularly good results will be obtained where the maker adhesive is of a conventional phenol-formaldehyde composition if the front size is also a phenol-formaldehyde composition. 0

Sand size coat 14, as is conventional in the abrasive art, may be of the same material as the maker coat or it may be of different material, as desired. In general, however, it is desired to have the sand size coat of the same resinous material as the maker coat.

The abrasive grains used can be of any of these materials used conventionallyin the manufacture of coated abrasive material. These include silicon carbide, alumina, garnet, flint, and diamond. Polycrystalline abrasive grain material of, e.g., fused zirconia-alumina, can also be used.

The following specific examples will illustrate more clearly how to practice our invention and the preferred embodiments thereof. 0

EXAMPLE 1 A 100 percent cotton sateens woven (4/ 1) fabric (53 inches wide, 0.92 yds. per lb.) of maximum construction, i.e., 98.5v percent fabric cover, yarn count 104 X 60 (warp fill), yarn number l7s cotton in warp and 6.5s cotton in fill, was singed and dyed according to usual techniques. It was then dried while held on a tenter frame to a width 1 inch widerthan the greige fabric.

The dyed, dry fabric was then saturated with Rexoslip AS, a non-slip agent formulation commercially available which had been diluted with water to 20 percent total solids, and adjusted with NH OH to a pH of 9.5. This was accomplished according to usual techniques by passing the fabric around a roll immersed in the non-slip composition and thence through the nip formed by such roll and another to squeeze out excess saturant. The wet fabric was then oven dried, after which it is transferred to a tenter frame and pulled to a width of 53% inches. The fabric was sufficiently impregnated with this non-slip composition to result in, on drying, an add-on weight of about 1.8 lbs. per sandpaper makers ream.

Next, the woven fabric was provided with a standard glue-calcium carbonate back-fill and back-size after which it was ready for application of the resinous front size. This was accomplished by passing the fabric through a Tommy Dodd and coating the twill side thereof with a composition comprising:

AMOUNT,

COMPONENT lbs.

. to which sufficient water had been added to result in a coating viscosity of 15,000centipoises (cps) at F. While a higher viscosity composition, e.g., up to 18,000

cps will be found satisfactory, 1 less than 13,000 cps, with this manner of application will be unsuitable. Ob,- viously, other means of application may be used rather than a Tommy Dodd involving resinous compositions of various viscosities.

The resinous front size is then dried to a tack free condition and caused to penetrate into the fabric by passing the wet coated fabric at 80 feet per minute over a series of hot cans (5 lb/in gauge steam). It is essential to obtain the desired degree of penetration that the coat side be away from. the hot can surface. An adequate amount of the front size composition was coated onto the fabric toresult in a dried front size weight of about 6.8 lbs. per sandpaper makers ream.

On examination under a microscope, the front size is seen in general to form a thin continuous layer on the fabric surface and to have'penetrated into the fabric to the extent of at least about 50 percent of its thickness. The resin penetration may exceed somewhat 50 percent of the fabric thickness, however, it will not extend in general beyond about 75 percent of the fabric. Measurement of the fabric width revealed a total pull down during finishing of only about 1% inches. Thus, a pull down of less than about 2.5 percent occurred.

EXAMPLE 2 The sateens cotton cloth, finished as disclosed in Example was trimmed to 50 inches'width and was then coated in conventional manner with a maker adhesive composition comprising the following ingredients:

Subsequent to application of the maker adhesive composition (viscosity 6,600 cps at F), silicon carbide abrasive grain (grit size 40) was deposited thereon (38 lbs. per sandpaper makers ream) by usual techniques. After this, the abrasive-adhesive coated backing member was heated, in accordance with established procedures known to those in the abrasive art, in a sandpaper drying room for 82 minutes in a stepwise fashion from 170 to 225F. A sufficient amount of maker adhesive composition was applied to result in a dried partially cured layer of 21.0 lbs. per sandpaper makers ream.

A size adhesive composition was prepared of the same formulation as the maker adhesive except that it was diluted with water to a viscosity of 800 cps at 100F. This composition was then applied (22.2 lbs. per sandpaper makers ream) to the abrasive-adhesive layer after which the thus coated backing member was again heated for 102 minutes stepwise over a temperature range of F to 230F. The thus coated web was then final cured for 8 hours at 235F for curing of the adhesive layers.

EXAMPLE 3 Coated abrasive material (46 inches wide), manufactured as disclosed in Example 2, was used to manufacir ture sectional abrasive belts I6, 6 3 1 44 inches similar to that shown in FIG. 2 of the drawing. This was accomplished by cutting, in known manner, sections 17 from the coated abrasive material in the shape of a parallelogram 48 X 65.9 inches, the acute angle A between EtEigLt sides beingllf 30. Y n V In general, the coated abrasive, web is withdrawn from a roll thereof and a first cut is made laterally and at the angle with respect to the running direction of the web required to obtain the desired angularity of joint when the abrasive sections are adhesively joined together. A second cut is made, parallel with the first cut edge, at a sufficient linear distance from the first cut edge that the longer altitude of the parallelogram thus formed is equivalent to the width of sectional abrasive belt desired. Thus, in the above-mentioned instance, the abrasive web was cut at an angle of 73 30' with respect to the longitudinal direction of the abrasive web, thus providing a cut edge measuring 48 inches. At a linear distance of 65.9 inches from the first cut edge, a second cut was made at the same angle as the first cut edge. A parallelogram shaped section of abrasive material is provided having a longer altitude of 63 inches.

Three such parallelogram shaped sections of abrasive material were then joined together (conventional lap joint but a butt joint would also be satisfactory) in the manner disclosed in FIG. 2, long side being joined to long side, to form an endless abrasive belt of the desired width. As seen from the drawing, when the sections of abrasive material are joined together, the warp At 100 lbs./in. width tensile strength, abrasive belts manufactured in accordance with the invention are found to elongate a maximum of only about 4 percent.

A control sectional beltin which the abrasive material had a standard sateens cotton cloth backing member, yarn count 96 X 60, yarn number l7s in warp and 9.5s in fill, 1.12 yd./lb., conventional glue-starch finish, and which was manufactured in the same manner and tested on the same grinding apparatus as the belt above-described resulted in excessive elongation after only 4 hours belt usage.

Although the finished cloth of this invention has been described particularly for use in the manufacture of sectional abrasive belts, other uses therefor will become obvious to those skilled in the art of cloth finishing. Moreover, in the abrasive industry, a desirable use other than in the manufacture of sectional belts involves usage of coated abrasive segments having such a backing member in the manufacture of abrasive flap wheels. In any event, it is to be understood that the specific embodiments of the invention as presented herein are intended by way of illustration only and not limiting on the invention but that the limitations thereon are to be determined only from the appended claims.

What we claim is:

1. In coated abrasive material comprising a backing member, an adhesive layer on the front side thereof, and a plurality of abrasive grains secured by said adhesive layer to said backing member, the improvement comprising a wove fabric backing member of maximum construction as shown by a fabric cover of at least about 98 percent and having on its front face a resinous composition comprising at least one heat hardened resin, said resinous composition penetrating into the woven fabric to the extent of at least about 50 percent of its thickness, said adhesive layer being compatible and miscible with said resinous front size whereby on curing of said layer and said front size a strong bond is formed therebetween.

.2. Endless coated abrasive belt in which sections of abrasive material in accordance with claim 1 are adhesively secured together, said sections being in the shape of a parallelogram, the longer sides of the parallelogram being joined together whereby a sectional belt of greater width than the width of coated abrasive material from which the sections are cut is provided, said sectional abrasive belt having no more than about 4 percent elongation at 100 lbs/in. width tensile strength.

3. In coated abrasive material according to claim 1, said woven fabric backing member including as an impregnant a non-slip agent for providing greater fiber-tofiber friction, said non-slip agent being applied to the fabric before application of said resinous front size.

4. In coated abrasive material according to claim 3, said non-slip agent comprising a mixture of hydrogenated resins.

5. In coated abrasive material according to claim 4, said resinous front size and said adhesive layer each comprising phenol-formaldehyde.

6. In coated abrasive material according to claim 5, said backing member comprising a cotton fabric of sateen construction having 'a 4/1 weave, a yarn count of 104 X 60 (warp X fill), and yarn numbers of ITS cotton in the warp and 6.5s cotton in the fill. 

2. Endless coated abrasive belt in which sections of abrasive material in accordance with claim 1 are adhesively secured together, said sections being in the shape of a parallelogram, the longer sides of the parallelogram being joined together whereby a sectional belt of greater width than the width of coated abrasive material from which the sections are cut is provided, said sectional abrasive belt having no more than about 4 percent elongation at 100 lbs./in. width tensile strength.
 3. In coated abrasive material according to claim 1, said woven fabric backing member including as an impregnant a non-slip agent for providing greater fiber-to-fiber friction, said non-slip agent being applied to the fabric before application of said resinous front size.
 4. In coated abrasive material according to claim 3, said non-slip agent comprising a mixture of hydrogenated resins.
 5. In coated abrasive material according to claim 4, said resinous front size and said adhesive layer each comprising phenol-formaldehyde.
 6. In coated abrasive material according to claim 5, said backing member comprising a cotton fabric of sateen construction having a 4/1 weave, a yarn count of 104 X 60 (warp X fill), and yarn numbers of 17'' s cotton in the warp and 6.5''s cotton in the fill. 